There is a consensus that animal, and especially rodent systems, are not ideal for the prediction of the carcinogenicity of various chemicals in humans. Apparently, different species vary in their capacity to repair deoxyribonucleic acid (DNA) after radiation injury, in a manner suggesting correlation with species longevity (Tice, et al. (1985) "DNA Repair and Replication in Aging Organisms and Cells", The Biology of Aging, C. E. Finch and E. L. Schneider, Eds., Pages 173-224, Van Nostrand Reinhold Company, New York and Sankar (1994) Science 266:1954-1956). Malignancies, too, may be correlated with species longevity (Kim, et al. (1994) Science 266:2011-2015). Thus, studies conducted with neoplastic transformation are more readily performed in rodent than in human cells in culture (Borek (1985) Carcinopenesis 10:303-316), clearly indicating a higher level of sensitivity to carcinogens in the former than in the latter system(s). Yet a system with human cells in culture to test carcinogenicity would obviously be highly desirable.